Apparatus for developing electrostatic images



Sept; 30, 1969 D. D. SLOAN 3,469,553

APPARATUS FOR DEVELOPING ELECTROSTATIC IMAGES V Fil ed July 18, 1967 a; A a 5 I 'JYI'I'". If...

United States Patent US. Cl. 118-325 3 Claims ABSTRACT OF THE DISCLOSURE Apparatus for developing electrostatic images comprising means for feeding exposed material over a roller with the image side of the material bearing on the roller and a nozzle for directing a stream of developer against the roller in the crotch between the roller and material, the nozzle comprising two opposed walls with a passageway therebetween for said stream, one wall being disposed between the material and stream and being shorter than the opposite wall to provide said turbulence space between the material and said opposite wall at the outer end of the nozzle, said passageway comprising grooves in said opposite wall which extend lengthwise of the stream, and the depth of said grooves decreasing toward the outer end of the nozzle.

This invention is an improvement on that described and claimed in my copending Patent 3,356,072 granted Dec. 5, 1967.

Objects of the present invention are to produce apparatus which is simple and economical to produce, which develops rapidly without cloudiness or streaking and which is durable and reliable in use.

According to this invention the apparatus comprises means for feeding exposed sheet material along a predetermined path, opposed squeegee members on opposite sides of the path for squeegeeing the material as it passes through the nip therebetween, the member on the image side of the material being a roller, and a nozzle for directing a stream of developer against the roller as close to the nip as possible without substantial impingement directly on the strip material. In this way vigorous turbulence of the developer is produced at the image face of the sheet material. Preferably the nip is directed downwardly so that the developer falls away from the nip by gravity, the apparatus having a developer reservoir below the nip to catch the falling developer and means for pumping the developer from the reservoir to the nozzle.

In a preferred embodiment of the invention the nozzle is directed along the aforesaid path with its outer end juxtaposed to the aforesaid roller, the side of the nozzle next to the sheet material being open to provide turbulence space in which the stream may swirl against the material as the material approaches the nip. Preferably the nozzle comprises two opposed walls with a passageway therebetween for the stream, one wall being disposed between the material and stream and being shorter than the opposite wall to provide the aforesaid turbulence space between the material and said opposite wall at the outer end of the nozzle. The passageway should comprise grooves in said opposite wall which extend lengthwise of the stream and the grooves preferably decrease in depth toward the outer end of the nozzle.

For the purpose of illustration typical embodiments of the invention are shown in the accompanying drawings in which:

FIG. 1 is a plan view of an improved nozzle with parts broken away;

3,469,563 Patented Sept. 30, 1969 ice FIG. 2 is a front view of the preferred nozzle with parts broken away; and

FIG. 3 is a section on line 3-3 of FIG. 2.

The present improvement shown in FIGS. 3 to 5 is like that shown in FIGS. 1 and 2 in that it comprises a pair of squeegee rolls 70 and 71, a tank 72, and a pair of rolls 73-74 for feeding the strip of exposed material M. However it differs in that the nozzle comprises a tube 76 having an inlet 77 and a passageway 78 leading to an outlet 79 directed toward the roller 71. The passageway is defined by an outer wall 81 which extends into juxtaposition to the roller 71 and an inner wall 82 which is much shorter. The space above the outer wall beyond the end of the inner wall forms a turbulence chamber which is substantially closed except on the side facing the material M, (the upper side in FIG. 5) the space being bounded on the top by the material M, on the bottom by the wall 81, on the side opposite the outlet 79 by the roller 71 and on the ends by the end walls 83 of the nozzle, The surface of wall 81 has grooves 84 to help distribute the developer throughout the length of the nozzle. A guide 85 holds the material close to the open side of the turbulence chamber as the material approaches the nip between the rollers 70 and 71.

From the foregoing it will be understood that the stream of developer does not impinge on the material M directly but that it swirls against the material from the end of the inner wall 82 to the roller 71, thereby developing the latent images on the material rapidly and uniformly without clouding or streaking the images.

I claim:

1. For developing electrostatic images on sheet material, apparatus comprising means for feeding the material along a predetermined path, opposed squeegee members on opposite sides of the path for squeegeeing the material as it passes through the nip therebetween, the member on the image side of the material being a roller, and a nozzle for directing a stream of developer against said roller in said nip, the nozzle being directed along said path with its outlet juxtaposed to the roller and the nozzle extending along said path a substantial distance in juxtaposition to said material, the side of the nozzle next to said material being open to provide turbulence space in which the stream may swirl against the material as the material approaches the nip, the nozzle comprising two opposed walls with a passageway therebetween for said stream, one wall being disposed between the material and stream and being shorter than the opposite wall to provide said turbulence space between the material and said opposite wall at the outer end of the nozzle.

2. Apparatus according to claim 1 wherein said passageway comprises grooves in said opposite wall which extend lengthwise of the stream.

3. Apparatus according to claim 2 wherein the depth of said grooves decreases toward the outer end of the nozzle.

References Cited UNITED STATES PATENTS 3,036,551 5/ 1962 Shreckhise 118-326 X 3,405,627 10/1968 Day et al 118-325 X 3,405,626 10/ 1968 Fleisher et al 118-405 X 2,653,566 9/ 1953 Worden 11'8-63 2,690,394 9/1954 Carlson 117-93.4 X

3,242,902 3/ 1966 Ulary 118-637 3,356,072 12/1967 Sloan 118-637 WALTER A. SCHEEL, Primary Examiner JOHN P. MCINTOSH, Assistant Examiner 

